The working principle of displaying one frame of image or data by using TFT-LCD (Thin Film Transistor-Liquid Crystal Display) is using a gate driving circuit to input a square wave signal into each row of pixels from the top row to the bottom row to select and enable rows of pixels. The square wave signal has a certain pulse-width. A source driving circuit may generate the output signal required for each row of pixels sequentially from the top row to the bottom row.
Currently, in many TFT-LCDs, the gate driving circuit and the source driving circuit are installed outside the display panel. This configuration can cause undesirably high cost. Thus, other alternative ways have been considered to lower the cost. For example, a gate driving circuit with a plurality of shift register units, i.e., GOA (Gate Drive On Array) circuit, has been designed and manufactured on the display substrate.
In the GOA circuit, the output timing includes an effective display period and a blank period. As shown in FIG. 3, specifically, when the display panel is displaying one frame, the outputs are in the effective display period. The shift register units. i.e., from the first shift register unit (G1) to the Nth shift register unit (GN), can scan the gate line connected to each shift register unit and output the scan signals. After each gate line is scanned, the circuit goes to the blank period. In the blank region, since none of the shift register units functions, the output potential of each shift register unit becomes 0 at the same time (because the output potential of a shift register unit is negative, the output changing to 0 V is a pull-up process). The pull-up process in the bank period causes the output of each shift register unit to be unstable.